1. Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic method.
2. Background Art
The image forming apparatus using the electrophotographic method is employed to produce various kinds of printed matter, in which the special toner may be employed for the printing. Herein, the printing with MICR (Magnetic Ink Character Recognition) will be described below as an example.
MICR means a system for printing a special calligraphic style called an MICR font on a part of the check or financial document using the magnetic ink and the magnetic toner (MICR toner), reading the MICR font by an apparatus called an MICR reader/sorter, and performing the processing such as classification. This MICR is widely spread especially in Europe and the United States.
The MICR toner contains a large amount of ferromagnetic particles of pure iron, ferrite, iron oxide or magnetite. If the MICR toner is employed for the printing apparatus, a fixing unit for fixing the MICR toner on the paper is greatly damaged on the surface of a heating roller by the ferromagnetic substance in the MICR toner, so that the life of the fixing unit is reduced to about one-third the ordinary length. Accordingly, if the MICR toner is employed in the printing without needing the MICR toner, a fixing roller is remarkably deteriorated and must be replaced frequently, whereby the cost is greatly increased.
Further, since the MICR toner is very expensive, the use of the MICR toner for the printing other than the MICR font increases the cost. The MICR font is only employed for the printing on apart of the check, and limited in the application.
The preprint is made employing a monochrome printer and a color printer for the normal printing, and then the MICR font is printed employing an MICR specific printer. In this case, the MICR specific printer has a lower frequency of use than in making all the printing, whereby the MICR specific printer is advantageous in the respect of the cost.